Conventionally, there has been known a mobile communication system that adopts a DRX (Discontinuous Reception) setting a duration in which a radio terminal monitors a downlink signal transmitted from a radio base station (hereinafter, referred to as “monitoring duration”) and a duration in which the radio terminal does not monitor the downlink signal transmitted from the radio base station (hereinafter, referred to as “non-monitoring duration”) (for example, Non Patent Literature 1). For example, as such a mobile communication system, LTE (Long Term Evolution) has been known.
The same DRX cycle is used in a cell managed by the radio base station. It is noted that as the DRX cycle configured by the monitoring duration and the non-monitoring duration, cycles of 0.32 seconds, 0.64 seconds, 1.28 seconds, and 2.56 seconds are defined.
Here, an opportunity in which the downlink signal (here, a paging signal) is transmitted from the radio base station to the radio terminal is allocated to match the above-described monitoring duration. That is, a paging cycle allocated with the opportunity in which the paging signal is transmitted is similar to the DRX cycle.
Incidentally, when the same DRX cycle (paging cycle) is used in the cell managed by the radio base station, the radio terminal is not capable of knowing in which monitoring duration the paging signal destined to the radio terminal is transmitted, and thus, even when the opportunity in which the paging signal destined to the radio terminal is transmitted is less than that of another radio terminal, it is necessary to monitor the paging signal destined to the radio terminal in all the monitoring durations.
Therefore, when the same DRX cycle (paging cycle) is used in the cell managed by the radio base station, it is not possible to sufficiently reduce a power consumption of the radio terminal having less communication opportunities.